Towards the final Gaia catalogue

In the early 2020s, the final Gaia catalogue will be published. This will be the definitive stellar catalogue for the foreseeable future, playing a central role in many and varied fields of astronomy.

Producing this final catalogue is a complicated endeavour that requires the entire mission dataset and a complex processing chain devised and tested by hundreds of scientists and software experts in the Gaia Data Processing and Analysis Consortium (DPAC).

Even before the first data release special subsets of Gaia data were made public to facilitate timely follow-up observations by the wider astronomical community. For example, Science Alerts – announcements to the scientific community about detected transient events such as supernovae and outbursting stars – were, and continue to be, regularly issued. The Gaia coordinates for one particular star were made available, in advance of the data release, to astronomers studying a rare occurrence of Pluto passing in front of this star.

Following the first data release in September 2016, the release of new datasets, based on longer time intervals and with additional data products, are planned to take place with a cadence of about one per year. These will be characterised by increasingly improving precision and additional parameters for the surveyed stars, as well as for other celestial objects – from Solar System bodies to galaxies beyond our Milky Way.

Eventually, the final catalogue will contain full astrometric (position, distance and motion) and photometric (brightness and colour) parameters for over one billion stars as well as extensive additional information including a classification of the sources and lists of variable stars, multiple stellar systems and exoplanet-hosting stars. For more than 150 million stars there will be measurements of the radial-velocity – the speed at which the star is travelling towards or away from us. The final Gaia catalogue will be a census of our Galaxy of such superb precision and detail that it will redefine the fundamental reference frame used for all astronomical coordinate systems. This will truly mark a new era of astrometry.